1. Field of the Invention
Dietary fiber is considered to be the soluble and insoluble components of food that are not digested by enzymes in the human gastrointestinal tract. The primary sources of dietary fiber include such cell wall materials as cellulose, hemicelluloses, lignin, and pectins, along with gums and mucilages. Dietary fiber has been considered an important food component since early times. Recently, Burkitt et al. [Lancet 2: 1408-1411 (1972)] concluded that dietary fiber has a role in the prevention of certain large-intestine diseases, including cancer of the colon and diverticulitis. Diets containing large amounts of dietary fiber lead to stools that are softer and larger, and bowel movements are generally more frequent. Burkitt also mentioned that the serum cholesterol rises when dietary fiber is removed from the diet, and that eating a fiber-rich diet lowers serum cholesterol. Trowell [Am. J. Clin. Nutr. 25: 464-465 (1972)] reached a similar conclusion regarding the relationship between fiber and health benefits.
It is now known that all dietary fiber is not the same and that different fibers provide different health benefits. For example, wheat bran is very rich in insoluble dietary fiber (mainly cellulose and hemicelluloses) and is excellent for decreasing the transit time of food through the digestive tract [Anderson et al., Am. J. Clin. Nutr. 32: 346-363 (1979)]. Some fibers are reported to reduce total plasma cholesterol [Munoz et al., Am. J. Clin. Nutr. 32: 580-592 (1979)]. This invention relates to a novel food composition from oats that provides soluble dietary fiber useful as a functionally and nutritionally advantageous ingredient for a variety of food products.
2. Description of the Prior Art
The first indication of serum cholesterol lowering by rolled oats was observed in rats by Degroot et al. [Lancet 2: 303-304 (1963)]. Fisher et al. [Pro. Soc. Exp. Biol. Med. 126: 108-111 (1967)] report that the fiber fraction of oats is responsible for its unique effects on cholesterol. Over the years, numerous experiments with animals have shown that oat fiber has a strong hypocholesterolemic effect. Anderson et al. [Am. J. Clin. Nutr. 34: 824-829 (1981); 40: 1146-1155 (1984)] have confirmed hypocholesterolemic effects of oats in humans.
It is the soluble fiber that is effective in lowering cholesterol levels. Oatmeal, or rolled oats, and especially oat bran are the best sources of this soluble fiber. Moreover, oat fiber reduces the amount of low density lipoprotein (LDL) without lowering the beneficial high density lipoprotein (HDL). In fact, Anderson et al. [66th Annual Meeting, Am. Assoc. Cer. Chemists, Abstract No. 112 (1981)] teach that oat bran fed to humans can reduce LDL 58% while increasing HDL 82%. Other water-soluble fibers, such as pectin and guar gum, can lower serum cholesterol, but they are frequently accompanied by undesirable side effects such as nausea and vomiting. The results of another study by Anderson et al. (supra, 1984) indicate that oat bran diets decrease total serum cholesterol 19% and LDL 23% and that oat bran increases bile acid excretion 65%. These studies clearly document the hypocholesterolemic effects in humans of oat products which are rich in soluble fiber.
In the art of starch hydrolysis, it is known that starch can be hydrolyzed by acids or enzymes to give a variety of products with properties depending on the degree of conversion. Acid conversions are known to give uniform distribution of hydrolysate fragments because of the random cleavages of the starch molecule, whereas enzymes result in variations in amounts of the different oligomer fragments [Inglett, J. Food Biochem. 11: 249-258(1987)]. Various amylolytic enzymes are used in the thinning or liquefaction of starch and in the production of low conversion starch hydrolysates which are known in the trade as maltodextrins or corn syrup solids, depending upon the degree of hydrolysis (Morehouse, U.S. Pat. No. 3,663,369). It is also recognized that specific maltodextrins can be prepared at a D.E. within the range of 10-13 (Coker, U.S. Pat. No. 4,447,532). The starches used to prepare maltodextrins are obtained primarily from the wet milling of corn. Other sources of starch for commercial products are tapioca, potato, and rice.
Whole cereal flours have also been subjected to starch-hydrolyzing conditions and have yielded, for example, a whole-grain hydrolyzed product (Conrad, U.S. Pat. No. 4,377,602) and a ready-to-eat, enzyme-saccharified cereal (Fulger et al., U.S. Pat. No. 4,710,386). Ronai (U.S. Pat. No. 3,640,729) arrives at a similar product by adding prehydrolyzed starch to oat flour to yield an instant oat cereal product.